Voltage transient monitor

ABSTRACT

A system is provided for measuring and recording high-speed transients occurring on a powerline or other voltage source, using a relatively slow speed recorder. The transient is quantized into discrete amplitude steps and discrete duration increments. The resulting digital values are then stored, and subsequently displayed on the recorder.

United States Patent Raymond E. Johnson;

Abraham Levine, both of Ft. Lauderdale, Fla.

Mar. 4, 1970 Jan. 4, 1972 Data Research Corporation Ft. Lauderdale, Fla.

Inventors Appl. No. Filed Patented Assignee VOLTAGE TRANSIENT MONITOR 9Claims, 2 Drawing Figs.

US. Cl 324/102, 324/113, 324/181 Int. Cl G01r 27/28, GOlr 13/04 Field ofSearch 324/ 102,

rren Source Curren Source 3- Sec. Timer [56] References Cited UNlTEDSTATES PATENTS 2,752,589 6/1956 De Long, Jr. 324/103 X 3,054,960 9/1962Pearlman 324/103 X 3,241,065 3/1966 Leah 324/99 3,440,537 4/1969 Warneret a1 324/99 X Primary Examiner-Rudolph V. Rolinec AssistantExaminer--Emest F. Karlsen AttorneysWilliam D. Hall, Elliott I. Pollock,Fred C. Philpitt, George Vande Sande, Charles F. Steininger and RobertR. Priddy ABSTRACT: A system is provided for measuring and recordinghigh-speed transients occurring on a powerline or other voltage source,using a relatively slow speed recorder. The transient is quantized intodiscrete amplitude steps and discrete duration increments. The resultingdigital values are then stored, and subsequently displayed on therecorder.

Recorder Pmmmm 4m ammo SHEET 1 BF 2 Recorder Current INVENTORS 9 RaymondE. Johnson A bro/mm Levine ATTORNEY PATENTED JAN 41972 SHEET 2 BF 2 omvmv S3550 3:22am

rnazm 320a 292mm 5 E5 INVENTORS Raymond E Johnson Abraham LevineATTORNEY VOLTAGE TRANSIENT MONITOR BACKGROUND OF THE INVENTION As iswell known, power malfunctions in various types of electrical systemscan result in highly undesirable transients. Since the occurrence ofsuch transients, or other undesired voltage variations, can causesignificant problems in the operation of an overall system, it isdesirable to be able to provide an indication and/or classification ofthe characteristics of a voltage source, including transients which mayoccur.

A major problem in monitoringtransients involves the fact that the timeof occurrence, amplitude, and duration of a transient is normallyunpredictable. Moreover, when a transient does occur it is normally ofbrief duration; and therefore it is entirely possible that occurrence ofa transient may not be immediately observable due simply to its fleetingnature. In order, therefore, to properly monitor a transient, anapparatus should be provided which is continually operable to sensepredetermined characteristics of a voltage source; and the apparatusemployed should preferably include means for indicating just when atransient has occurred, as well as the nature of the transient.

To the extent that efforts have been made in the past to monitortransients, the work done heretofore has concentrated on improving thetypes of display system or recorder unit to be used in order thatshort-duration transients can, notwithstanding their brief occurrence,provide a meaningful output indication. To this effect, efforts havebeen made to improve the sensitivity, speed, or nature of the recordingmechanism and/or display mechanism employed, in an effort to betterdisplay and/or record the transient itself. Approaches of this type haveresulted in complex and costly systems which, nevertheless, haveexhibited relatively erratic operation.

The present invention, rather than seeking to record a transient itself,used a different approach for transient monitoring. To this effect, thepresent invention uses a transient to control a plurality of detectorsoperative to produce digital signals related to the amplitude andduration of a transient; and these digital signals are stored andsubsequently displayed on, or used to control, a conventional relativelylow speed recording device. By this approach, the difficulties inherentin trying to record the transient itself are avoided; and major circuitsimplification and cost reductions are achieved along with improvedreliability in the transient monitoring operation.

SUMMARY OF THE INVENTION The present invention is concerned with unitsadapted to continuously monitor a voltage point (power line or othervoltage source) and to provide an indication and/or classification ofany predetermined characteristics of that source, such as anout-of-tolerance voltage. While the unit is referred to herein as avoltage monitor, it will be apparent to those skilled in the art that,by use of a current transformer or shunt, the system also has thecapability of monitoring outoftolerance current conditions; andaccordingly the term voltage is intended to voltage-monitoring genericto both currentand voltage-monitoring operations.

The device of the present invention finds application in computer roomsto monitor AC power, thereby to determine when the contents of acomputer program might have been altered by a powerline transient. Thedevice can also be used to monitor AC power for automatic machinery suchas for the process control for monitoring the sync signal on TV stationsto detect dropout of sync; to monitor AC or DC power during acceptanceor qualification testing of equipment, so that tests need not berepeated if an out-of-tolerance powerline transient occurs; to monitorlines giving pressure or temperature for alarm conditions; for debuggingcomplex systems having transients on the lines, such as aircraft flighttest and missile launches; or for monitoring voltage and/or currentconditions at power generating stations.

rality of threshold detectors. One group of thesedetectors is providedfor quantizing transient amplitude, and a different.

group of detectors is provided for quantizing transient duration. Eachdetector, in both groups, is provided with a reference potentialestablishing, for that detector, a predetermined operating threshold.

When a transient occurs, it is applied simultaneouslyto all of thethreshold detectors forming the amplitude quantizing portion of thesystem. Various ones of the amplitude threshold detectors will beoperatedin dependence upon the actual amplitude of the appliedtransient; and those threshold detectors which are actually operated inturn drive storage latches, which may take the form of bistable devices,operative to quantize the transient amplitude into digital values. Inthis way, the transient amplitude is used to produce a digital signalwhich can be stored for an extendedperiodof time consistent with displayon a relatively slow speed recorder. The outputs of the latches or othermemory elements employed are used to drive a digital-to-analogconverterwhich in turn feeds a signal to the recorder for purposes ofdisplaying the transient amplitude.

Occurrence of a transient also initiates generation of a linear voltageramp; and the ramp voltage increases progressively until it is halted bytennination of the transient. By this technique, the magnitude achievedby the voltage ramp is directly related to the duration of thetransient. The generated ramp is applied to the inputs of the severalthreshold detectors forming the transient duration monitoring portion ofthe system, and operates selected ones of'these duration thresholddetectors in dependence upon the magnitude of the voltage ramp. As inthe case of the amplitude quantizing portion of the system, the outputsof the operated duration threshold detectors again drive latches orother appropriate memory elements thereby to convert the transientduration into digital values which may be stored; and the output of thisfurther memory portion of the system in turn drives another digital toanalog converter feeding a duration signal to the recorder for displaypurposes.

The recorder employed can take the from, of a two-channel strip chartrecorder adapted to display. amplitude information in one channel, andduration information in the other channel. Alternatively, the recordingunit can comprise a single channel strip recorder with the amplitude andduration information being multiplexed. As will become apparent,moreover, systems constructed in accordance with the present inventionmay be used to monitor DC voltages or AC voltages; and they may also beemployed to monitor positive-going and/or negative-going transients.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic diagram of one form oftransient monitor constructed in accordance with the present invention;and

FIG. 2 is a generalized functional diagram of systems constructed inaccordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 depicts the circuit fora voltage transient recorder constructed in accordance with the presentinvention; and, for purposes of illustration, the unit will be describedwith reference to the monitoring of DC voltages. In addition, forpurposes of illustration, the unit to be described in reference to FIGS.1 will be described with reference to the detection of transient levelshaving voltages greater than or equal to 30 volts, 40 volts, 60 volts,80 volts, and I volts; and for the detection of transient durations oftime intervals greater than or equal to l millisecond, 50 milliseconds,100 milliseconds, and 200 milliseconds. It must be emphasized, however,that these particular transient levels and durations are illustrativeonly; and other voltage levels and durations may be employed.

The voltage being monitored is supplied to an input terminal 10. Inaddition, a power supply (not shown) will normally be provided forpurposes of energizing the various components comprising the circuit ofFIG. 1. Actually, the power input to the unit may, if desired, bederived from the same source as the voltage being monitored; and if thistype of arrangement is not employed, isolation between the power andmonitored voltage inputs can be provided by means of a DC to DCconverter so that potential differences between the two voltages may beas much as several hundred volts. In addition, appropriate voltageregulators are provided so that the operating voltages appearing, forexample, at terminals such as ll constitute a regulated DC potential.

The input voltage being monitored, and applied to terminal 10, isapplied simultaneously to amplifiers A, and A through resistors 12 and13. Resistors l2 and 13 provide a high input impedance (e.g., lOOKohms), and also determine the gains of amplifiers A, and A when ratioedwith resistors 14 and 15 respectively. Amplifiers A, and A actually havegains less than unity in the particular embodiment to be describedbecause of the range of voltages which is to be accommodated (i.e., arange of 30 volts to 100 volts), so that the gain can be optimized foreach set of threshold detectors, to be described. Further amplifiers A,and A are coupled respectively to the outputs of amplifiers A, and A andoperate in turn to supply inputs to the several threshold detectors tobe described. Amplifiers A and A, are unity gain inverters, and operateto restore polarity of the input signal so that threshold detectorsoperating above ground can be used.

The output of amplifier A is coupled via line 16 to one input each of apair of threshold detectors 17 and 18. Each detector (as well as theother detectors to be described) comprises a differential amplifier ofintegrated circuit configuration. Moreover, each detector has one of itsdifferential inputs referenced to a voltage divider to establish anoperating threshold level or trip point for the detector in question.Thus, the input 17a of threshold detector 17 is coupled to a voltagedivider comprising a resistor 17b and a potentiometer 170 connectedbetween regulated DC source 11 and ground; and potentiometer 17c is soadjusted that threshold detector 17 will trip when a voltage of volts orgreater is applied to its other input 17d from the output of amplifier ABy a similar arrangement comprising a threshold circuit 18a, thresholddetector 18 may be caused to trip when the voltage applied to its input18b, from line 16, equals or exceeds 40 volts.

Amplifier A, is coupled, via line 22 to the inputs of a further set ofthreshold detectors comprising detectors 19, 20 and 21. Each of thedetectors 19, 20 and 21 is similar in construction and operation to thedetectors l7 and 18 already described; and each detector in this furtherset of detectors includes a threshold circuit on one of its differentialinputs so adjusted that threshold detector 19 will trip when a voltageof 60 volts or greater is applied to its other input 19a; detector 20will trip when a voltage of 80 volts or greater is applied to its otherinput 20a; and detector 21 will trip when a voltage eof 100 volts orgreater is applied to its other input 210. By this arrangement,therefore, and depending upon the magnitude of the transient whichappears at input 10, within the voltage range 30 volts to 100 volts,different ones of detectors 17 through 21 will be tripped or renderedoperative.

The outputs of detectors 17 through 21 inclusive are coupledrespectively to one input each of gates G, through G inclusive, asillustrated. The second inputs of the several gates G, through G areinterconnected to one another and, via line 23, to the output of aSOD-millisecond timer 24. Timer 24 is selectively triggered intooperation by means of a signal applied via line 25 from the output ofthreshold detector 17. The operation of this portion of the circuit willbe described subsequently.

The output terminals of the several gates G, through G, inclusive arecoupled respectively to one input each of a plurality of latches FF,through FF,,, comprising bistable circuits. Each latch includes a resetinput which is coupled via line 26 to the output of a 3-second timer 27;and the input of 3-second timer 27 is connected to line 25 for operationinresponse to a signal at the output of threshold detector 17.

The outputs of the several latches FF, through FF, are individuallycoupled via resistors R, through R, inclusive and an amplifier A to oneinput 28a of a recorder 28. In the particular embodiment illustrated,recorder 28 is assumed to com-' prise a two-channel strip chartrecorder, and information supplied to its input 28a is recorded in onechannel of the recorder as transient magnitude information. Similarly,and as will become apparent, information supplied to its other input28b, will be recorded on the other channel of said recorder as durationinformation.

The portion of the circuit thus far described is adapted to monitor theamplitude of a transient. Further elements are provided for monitoringtransient duration; but before describing these additional elements, adescription of the amplitude-monitoring portion of the system will begiven.

So long as the voltage on input terminal 10 is less than 30 volts, noneof detectors 17 through 21 will be tripped. For this condition ofoperation, timers 24 and 27 are off; gates G, through G inclusive areall disabled; no setting inputs are applied to any of latches FF,through FF,; and no input is supplied via 28a to recorder 28. Uponoccurrenceof a transient at terminal 10 having an amplitude of at least30 volts, however, the trip point of detector 17 will be exceeded; andthe output of detector or voltage comparator 17 will go high (in atypical case, it may now go to a voltage equal to or greater than 2.5volts). The output of detector 17 initiates, via line 25, operation ofthe SOO-millisecond interval timer 24. The output of said timer 24 iscoupled via line 23 to an input of each of gates G, through G to enableeach gate. T he simultaneous occurrence of an output from detector 17and an enabling input to gate G, from timer 24 thus permits gate G, toproduce a set input to latch FF and latch FF, is accordingly renderedoperative to produce an output via resistor R,.

In effect, for the operation thus far described, the occurrence of atransient having an amplitude of at least 30 volts has operated to setlatch FF, to produce a digital signal or stored indication that atransient of at least 30 volts amplitude has occurred.'By a similarsequence of steps, if the transient actually has an amplitude of 40volts or greater, detector 18 will also be triggered so that both oflatches FF, and FF, will be set. If the transient amplitude is actually60 volts or greater, all three detectors 17, 18 and 19 will be tripped,and all three latches FF,, FF,, and FF,, will be set; a transient havingan amplitude of at least volts will similarly set latches FF, throughFF, inclusive; and an input transient having an amplitude of at leastvolts will set all of latches FF, through FF,, inclusive.

Thus, the input transient is effectively quantized by causing differenttones of latches FF, through FF to be set in dependence upon theamplitude of the input transient; and the latches remain in their setcondition to store this quantized information for a sufficient timeinterval to permit the subsequent recording thereof on a relatively slowspeed recorder such as 28.

Resistors R, through R, inclusive comprise a resistor pro portionaladder acting, in effect, as a digital to analog converter, The actualsignal supplied to input 28a of recorder 28 thus depends upon how manyof the several latches FF, have been set; and this in turn causes therecorder 28 to display transient amplitude information. The output ofdetector 17, in addition to initiating operation of 500-millisecondtimer 24, also initiates operation of a 3-second timer 27. Upon elapseof the 3-second time interval of timer 27, a signal applied via line 26resets all of latches FF, through FF Thus, the operation of the systemquantities the input transient into discrete amplitude steps, storesthis quantized information, and provides a 3-second time interval forthe recording of the resultant information, whereafter the unit isautomatically reset for the detection and recording of a furthertransient.

Turning now to the transient duration monitoring portion of the system,it will be seen that the output of detector 17, in addition toperformingthe functions already described, is coupled to the inputs of apair of current sources 29 and 30. By this arrangement, sources 29 and30 are turned on" whenever the input voltage at terminal is at least 30volts; and said current sources 29 and 30 are turned off whenever theinput voltage falls below 30 volts. The outputs of current sources 29and 30 are coupled respectively to capacitors 31 and 32 and act tochargesaid capacitors when said current sources are on. In this way, theamount of voltage charge on capacitor 31 and/or 32 is directly relatedto the duration of the transient, i.e., the time that the voltage levelat terminal 10 was equal to or greater than 30 volts.

Capacitors 31 and 32 drive respectively a pair of buffers B and B whichin turn feed one side of each of four duration comparators or detectors33 through 36. Each of the detectors 33 through 36 is constructed in amanner similar to that already described with reference to detectors 17through 21; and, to this effect, each detector includes an inputthreshold circuit for setting the level at which the detector inquestion is tripped. The actual settings, and the points at which thedetectors 33 through 36 are tripped, are indicative of transientduration inasmuch as the actual magnitude of the voltage applied to theinput of said detectors from buffers B, and B is in turn derived from avoltage ramp which was initiated by first occurrence of the transient.The setting of the threshold for detector 33 is such that detector 33 istripped to its high state when a transient equal to or greater than 1millisecond has occurred. The settings of detectors 34, 35 and 36 aresuch that said detectors are tripped, respectively, upon occurrence oftransients equal to or greater than 50 milliseconds, 100 mil liseconds,and 200 milliseconds. Inasmuch as a relatively wide ratio exits betweenthe time base of detector 33, and the time bases of detectors 34, 35 and36, a separate buffer B is provided to drive detector 33, while buffer Bdrives all of detectors 34, 35 and 36.

The outputs of detectors 33 through 36 are connected respectively togates G through G which are entirely similar in structure and operationto gates 6, through G already described. Similarly, the outputs of gatesG through G are coupled respectively to one input each of latches FF6through F1 9 which correspond in structure and function to latches FF]through FFS already described. Gates G through 6,, are selectivelyenabled by a signal coupled via line 23a from the output ofSOD-millisecond timer 24; and latches FFo through FF9 are eventuallyreset by a signal applied via line 26a from the output of 3-second timer27. The operation of these portions of the circuit, and theirtiming inrelation to the portions already described, is thereforeidentical tothat which occurs in the amplitude quantizing portion of the system.

The outputs of flip-flops FF6 through F F9 are fed via a resistorproportional adder R through R, (similar to adder R,-R alreadydescribed), and via an amplifier A to the second input 28b of recorder28 to provide a transient duration input to said recorder.

In operation, occurrence of a transient at terminal 10 i.e., a voltageof at least 30 volts) operates, via an output signal from detector 17,to turn on current sources 29 and 30 to start charging capacitors 31 and32. The capacitors continue charging so long as the transient ispresent, and the capacitor charg ing is terminated only when the voltageat terminal 10 falls below 30 volts to cause the output from detector 17to cease and to cause current sources 29 and 30 to go off." As a result,capacitors 31 and 32 produce voltage ramps the magnitudes of which are ameasure of the time duration of the transient.

The capacitor voltages are coupled via buffers B and B to the inputs ofdetectors 33 through 36; and different ones of said detectors willaccordingly be tripped in dependence upon the magnitude of the capacitorvoltages, i.e., upon the time duration of the transient. The outputs ofthe detectors which have been tripped are coupled respectively viaenabled gates G through 6,, to set appropriate ones of flip-flops FF6through FF9. By this overall operation, therefore, the transient isquantized into discrete duration increments which are, in effect, storedas digital signals in the group of latches FFo through FF9. The outputsof the latches FF 6 through FF9 operate a digital to analog converter,i.e., proportional adder R -R to provide a duration information signalat 28b which is recorded on the second channel of the two-channel stripchart recorder 28.

The capacitors 31 and 32 are discharged completely at the end of theSOO-millisecond sample period provided by timer 24 in order to ready thecircuit for occurrence of a next transient. Separate discharge circuitsare provided for capacitors 31 and 32, and these have been indicated at38 and 39 respectively. The 3-millisecond timer 27 operates to resetlatches F1 6 through FF9, along with latches FF 1 through F F5, afterelapse of the 3-second interval necessary to display the amplitude andduration information on the strip chart recorder. The 3-second timer 27also inhibits additional transients from being measured during the3-second timer interval.

It will be appreciated, of course, that the number of threshold stepsemployed in both the amplitude and the duration quantizing portions ofthe system can differ from those described, and that, in addition, theactual quantizing levels can differ from those described. The system maybe modified to monitor AC signals instead of DC signals, and/or tomonitor negative-going as well as positive-going transients, and/or torecord on a signal channel recorder (by use of multiplexing techniques)rather than on a multiple-channel recorder. Other variations can also bemade. For example, the recorder can run constantly or, if desired, canbe actuated only when a transient has been detected. If desired, audibleand/or visible alarms can be provided to indicate that a transient hasoccurred; and relay closures or other control features may beincorporated to operate external equipment, or to inhibit operations ofequipment. In order to illustrate some of these further aspects of thenovel system contemplated herein, reference will now be made to FIG. 2which constitutes a generalized version of the specific circuit alreadydescribed in reference to FIG. 1.

As illustrated in FIG. 2, and as already described, the general systemis adapted to receive both a signal input 40 and a power input 41. Thesignal input constitutes, of course, the signal being monitored. It maybe either an AC or a DC signal, and may or may not be taken from thesource supplying power to the unit. Power supply 42 provides the voltagenecessary to operate the system and may operate with DC or AC inputs. inthe simplest case, input 41 to supply 42 can be a battery.

The input signal 40 should, as a general matter be coupled to a signalconditioner 43. Signal conditioner 43 provides amplification,attenuation, impedance matching, rectification if necessary, or acombination of these functions necessary to meet interfacespecifications and provide the detection circuitry with a usable signal.If the signal 4-0 is a DC signal, the signal conditioner 43 mayconstitute only a resistor network to provide attenuation, or anamplifier to provide gain. lfthe input signal is AC, the conditioner 43may include current transformers, amplifiers, and rectifiers operativeto convert the AC input into a DC or pulsed DC signal fortransientmonitoring and system-timing purposes.

Signal conditioner 43 drives a timing generator 44 which provides asampling window, and also provides logic timing. In the circuit alreadydescribed in reference to FlG. 1, the timer 24 provided, in effect, aSOD-millisecond sampling window. in the event that AC signals aresupplied to input 40, and are converted into pulsating DC by signalconditioner 43, the timing generator 44 can operate to select aspecified portion of each halfawave as the sample to be used foramplitude and duration monitoring purposes. 1

Power supply 42, in addition to supplying voltages necessary to operatethe system at 421, drives a reference generator 45 to provide aprecision reference or threshold for the several comparators 46 through51 inclusive. In the system described in reference to FIG. 1, thisreference was a regulated DC voltage. However, the reference mayconstitute a phase-locked AC voltage when AC voltages are beingmonitored. In this latter form of the invention, the timing signalprovided by timing generator 44 is preferably coupled, as at 45a, toreference generator 45 to provide synchronization with the input signal.

The threshold detectors 46 through 51 correspond to the circuits alreadydescribed in reference to FIG. I, and comprise integrated circuitcomparators which produce an output when the input supplied to eachcomparator equals or exceeds the value of the threshold for thatcomparator. Various trip voltages can be set up by use of potentiometers46a through 51a at the inputs of detectors 46 through 51. In addition,if desired, an optional timing input can be supplied to the comparators46 through 51 to implement the sampling window.

In the generalized circuit shown in FIG. 2, illustrative comparators 46and 47 have been assumed to constitute means for quantizing theamplitude of positive-going transients; and these detectors accordinglyoperate in the manner already described in reference to FIG. 1 toproduce output signals when their thresholds are exceeded. Theillustrative comparators 48 and 49, in the generalized circuit of FIG.2, are provided to quantize negative-going transients; and theyaccordingly produce outputs when their thresholds are not exceededduring the sampling interval. Illustrative comparators 50 and 51 operateto quantize transient duration; and, to that effect, receive an inputfrom a ramp generator 52 in the manner described previously. Rampgenerator 52 is turned on by an input from either high voltage detector47 or low-voltage detector 49 via OR-gate 53.

The first group of detectors 46-47, for monitoring positivegoingtransients, is coupled to a control logic circuit 54. Similarly, the lowvoltage group of detectors 48, 49 is coupled to control logic 55; andthe duration monitoring group of detectors 50, 51 is coupled to controllogic 56. The control logic blocks 54, 55 and 56 provide memorycompatible signals which are coupled respectively to memory 57. Memory57 in turn provides storage of transient amplitude and durationinformation until it can be displayed on the recorder 58.

The information stored in memory 57 is, as described previously digital;and flip-flop binary elements can accordingly be employed to store thisinvention. It will be appreciated, however, that other types of digitalstorage can be used. The output of memory 57 is coupled to a digital toanalog converter 59 which provides the DC voltages necessary to operaterecorder 58 from the digital information stored in memory 57. A timer 60can also be provided to control the display interval for the recorder58; and, if it is desired to display both amplitude and durationinformation on the same channel, timer 60 can be employed to multiplexthe signals to recorder 58.

While we have thus described preferred embodiments of the presentinvention, many variations will be suggested to those skilled in theart. It must therefore be emphasized that the foregoing description isintended to be illustrative only and not limitative of the invention;and all such variations and modifications as are in accord with theprinciples described are meant to fall within the scope of the appendedclaims.

Having thus described our invention, we claim:

1. A transient monitor for measuring high-speed voltage transientsoccurring at a voltage source and for recording said transients on aslow-speed recorder, comprising input means adapted to be coupled tosaid voltage source, said input means including reference means formonitoring the magnitudes of voltages supplied by said source to detectoccurrence of a transient, amplitude-quantizing means responsive todetection of a transient b said reference means and to the amplitude ofsaid transient or producing first digital signals related to theamplitude of said transient, duration quantizing means coupled to saidinput means and responsive to detection of a transient by said referencemeans and to the duration of said transient for producing second digitalsignals related to the duration of said transient, memory means forstoring said first and second digital signals, means coupled to saidmemory means for converting said stored first and second digital signalsinto analog signals related respectively to the amplitude and durationof said transient, and means supplying said analog signals to aslow-speed analog recorder means for displaying information related tothe amplitude and duration of said transient.

2. The monitor of claim 1 wherein said reference means comprises aplurality of voltage detectors, and means establishing differingoperating thresholds for differing ones of said detectors wherebyselected different ones of said detec tors are rendered operative independence upon the amplitude of said transient. I

3. The monitor of claim 2 wherein said amplitude-quantizing meansincludes a plurality of bistable devices coupled respectively to saidplurality of detectors.

4. The monitor of claim 1 wherein said duration-quantizing meansincludes means for initiating generation of a linear ramp voltage uponcommencement of said transient and for terminating generation of saidramp voltage upon cessation of said transient, and means responsive tothe terminated magnitude of said ramp voltage for producing said seconddigital signals.

5. The monitor of claim 4 wherein said means responsive to the magnitudeof said ramp voltage comprises a plurality of voltage detectors, saidramp voltage being supplied to the inputs of all of said plurality ofdetectors, and means establishing differing operating thresholds fordiffering ones of said detectors whereby selected different ones of saiddetectors are rendered operative in dependence upon the duration of saidtransient.

6. The monitor of claim 4 wherein said linear ramp voltage is generatedby a current source having capacitor means coupled thereto.

7. The monitor of claim 1 including timer means operable to clear saidstored first and second digital signals from said memory means at apredetermined time interval subsequent to detection of the occurrence ofsaid transient.

8. The monitor of claim 1 wherein alternating current voltages aresupplied by said source, said input means comprising means forrectifying the voltages being monitored, and means coupling saidrectified voltages to said reference means.

9. The monitor of claim 1 wherein said recorder means comprises atwo-channel recorder, said amplitude and duration information beingdisplayed respectively on separate channels of said recorder.

1. A transient monitor for measuring high-speed voltage transientsoccurring at a voltage source and for recording said transients on aslow-speed recorder, comprising input means adapted to be coupled tosaid voltage source, said input means including reference means formonitoring the magnitudes of voltages supplied by said source to detectoccurrence of a transient, amplitude-quantizing means responsive todetection of a transient by said reference means and to the amplitude ofsaid transient for producing first digital signals related to theamplitude of said transient, duration-quantizing means coupled to saidinput means and responsive to detection of a transient by said referencemeans and to the duration of said transient for producing second digitalsignals related to the duration of said transient, memory means forstoring said first and second digital signals, means coupled to saidmemory means for converting said stored first and second digital signalsinto analog signals related respectively to the amplitude and durationof said transient, and means supplying said analog signals to aslowspeed analog recorder means for displaying information related tothe amplitude and duration of said transient.
 2. The monitor of claim 1wherein said reference means comprises a plurality of voltage detectors,and means establishing differing operating thresholds for differing onesof said detectors whereby selected different ones of said detectors arerendered operative in dependence upon the amplitude of said transient.3. The monitor of claim 2 wherein said amplitude-quantizing meansincludes a plurality of bistable devices coupled respectively to saidplurality of detectors.
 4. The monitor of claim 1 wherein saidduration-quantizing means includes means for initiating generation of alinear ramp voltage upon commencement of said transient and forterminating generation of said ramp voltage upon cessation of saidtransient, and means responsive to the terminated magnitude of said rampvoltage for producing said second digital signals.
 5. The monitor ofclaim 4 wherein said means responsive to the magnitude of said rampvoltage comprises a plurality of voltage detectors, said ramp voltagebeing supplied to the inputs of all of said plurality of detectors, andmeans establishing differing operating thresholds for differing ones ofsaid detectors whereby selected different ones of said detectors arerendered operative in dependence upon the duration of said transient. 6.The monitor of claim 4 wherein said linear ramp voltage is generated bya current source having capacitor means coupled thereto.
 7. The monitorof claim 1 including timer means operable to clear said stored first andsecond digital signals from said memory means at a predetermined timeinterval subsequent to detection of the occurrence of said transient. 8.The monitor of claim 1 wherein alternating current voltages are suppliedby said source, said input means comprising means for rectifying thevoltages being monitored, and means coupling said rectified voltages tosaid reference means.
 9. The monitor of claim 1 wherein said recordermeans comprises a two-channel recorder, said amplitude and durationinformation being displayed respectively on separate channels of saidrecorder.